This invention relates to a fuel supplying system for internal combustion engines and more particularly to an improved fuel supplying system for two-cycle engines that improves fuel economy, cold running and cold starting.
As is noted in copending application Ser. No. 673,908 still pending, entitled "Fuel Supplying System For Internal Combustion Engine", filed Nov. 21, 1984 in the name of Yoshihiro Sakurai, and assigned to the assignee of this application, two-cycle engines present certain problems in connection with fuel condensation, particularly when operating at low temperatures and until the engine has warmed up. The fuel/air mixture, which is normally introduced into the crankcase, must travel a long distance from the crankcase through the transfer and/or scavenge passages to the combustion chamber before it is fired. Because of the long distance of travel, when the engine is at a low operating temperature, there is a likelihood of fuel condensation. Therefore, in order to compensate for this condensation, it has been the practice to provide additional enrichment fuel which considerably reduces the fuel economy and which oftentimes does not overcome the problem.
In accordance with the arrangement disclosed in that application, a separate charge former is provided that supplies a fuel/air mixture into the transfer passage and thus minimizes the length of travel and reduces the condensation problems. Although that arrangement is particularly advantageous, it itself has certain disadvantages and areas that could be improved. For example, there is a flow in both directions through the scavenge passage in that type of engine since the pressure in the combustion chamber at times exceeds the pressure in the crankcase and when the scavenge passage is still open. Under this condition, the fuel/air mixture supplied by the additional charge former will be returned to the crankcase where it can condense under low temperatures. In addition, the fuel must then flow back through the scavenge passage to the combustion chamber thus further increasing the likelihood of condensation.
It is also known that the initial intake charge from the scavenge passage is used to purge the residual gases from the combustion chamber and at least a portion of the initial intake charge flows out the exhaust port to insure good scavenging. With a device of the type shown in the aforenoted copending application, the initial charge of fuel and air delivered to the combustion chamber through the scavenge passage has large amounts of fuel and this fuel will be wasted if it is discharged through the exhaust port. In addition, under some running conditions, the velocity of the charge through the scavenge passage may not be sufficient so as to draw the required amount of fuel from the charge former provided in this passage.
It is, therefore, a principal object of this invention to provide an improved fuel supplying system for internal combustion engines.
It is a further object of this invention to provide a fuel supply system for internal combustion engines that will eliminate the likelihood of fuel condensation.
It is a yet further object of this invention to provide an improved fuel supply system for internal combustion engines that insures against the discharge of fuel through the exhaust port during the initial scavenging cycle.
It is a yet further object of this invention to provide a fuel supply system for internal combustion engines wherein the fuel is supplied in proximity to a high velocity air flow so as to insure good vaporization and fuel distribution.